What to buy next?

I am putting a set of XT brakes on my MTB & trying to decide on pads & rotors.

Some friends are saying only go Shimano rotor & pads.

Others say Shimano pads with Avid G3 or X or HSX rotor

Then next I here is organic pads are ok, but semi-metallic the best. Then others say organic all the way.. I am new to the disc stuff. My last bike was a 1996 Mongoose Amp II. This new bike I have had since June 2011.